His Constant
by Mally O'Jack
Summary: Lestrade loses his temper with Sherlock. And John teaches Sherlock about friendship.


I love Lestrade's line about Sherlock being a great man, and perhaps one day, a good one. And the unspoken implication that it is John who will make Sherlock good. So I guess I was thinking on that, and the whole concept of friendship, when I wrote this. Would love your feedback!

Set some time during the first season.

**His Constant **

by Mally O'Jack

Sherlock is twirling around the crime screen, moving his hands as if conducting an invisible orchestra. John smiles to himself, letting the words wash over him.

"And then the silver nitrate in the fingernails - oh that's clever – evidently an M.O, except why would a veterinarian leave an M.O? Unless -" He stops suddenly, snaps his fingers at Lestrade. "What did you say the name of the cat was?"

Lestrade doesn't respond.

John looks up from where he is leaning against the wall. "Greg?"

That gets his attention. "Yeah. Sorry, I was..." he trails off, clears his throat. "You were saying?"

Sherlock looks at Lestrade for a second. "What was the name of the cat?" He enunciates every word, as if speaking to a child. Behind him, John can see Donovan bristling.

"Cat?"

Sherlock hisses in frustration. "Oh, come on Inspector, just because your wife's left you again - "

There is a sudden burst of activity. Before John can intervene, Lestrade seizes the detective by the collar, and John sees a flash of – Shock? Hurt? Fear? in Sherlock's eyes before he is slammed against the wall.

"Finally," Anderson is saying, but John ignores him. "Hey - ", he says, stepping forward, but Lestrade cuts him off.

"When you're on _my_ crime scene," Lestrade says, close to Sherlock's face, "either you keep your trap shut, or piss off."

Sherlock regards Lestrade coolly, though John thinks he can detect a flush of colour in the usually pale cheeks. Then Sherlock drops his eyes submissively. Lestrade lets him go, breathing hard. Without looking up, Sherlock strides out the room.

"You all right?" says John quietly.

Lestrade nods. His palms are flat against the wall, his head bowed. Then he exhales deeply and turns round. "He was right. She did leave me. Yesterday."

"Ah."

Lestrade folds his arms around himself. After a moment, he says, "She won't be coming back this time."

John's brow tightens in sympathy. "Sorry," he offers.

"Yeah." With obvious effort, Lestrade straightens. "What was he saying about a cat?"

* * *

When John arrives back at the flat, he expects to see Sherlock already there. But the flat is dark. He flicks the lights on, wanders into the kitchen. Puts the kettle on.

Could it be that his flatmate was actually hurt by Lestrade's outburst? Was he off somewhere, sulking?

Top Gear's on in the background as he checks his emails, does some online banking. Reads a couple of medical journals. Then it's the ten o'clock news.

He's getting worried. He wants to text, but doesn't want to look as if he's molly-coddling Sherlock. The detective is a grown man after all.

An hour passes, and he texts anyway. _"Fancy a curry?"_

A couple of minutes later - _"No. SH." _

He's grateful that his flatmate has deigned to reply, but he still can't shake the niggling feeling that something is wrong.

The next day, John is at the clinic. He returns at tea-time, and for once is disappointed to find that the fruit bowl has not been replaced by a mould-ridden petri dish. Nor is his laptop serving as a microscope stand. Everything is exactly as he has left it.

* * *

Later that evening, he hears the key turning in the lock. Slow footsteps up the stairs. Sherlock appears in the doorway.

John is sitting in his armchair, waiting. He chokes down the "where have you been?", a line that sounds suspiciously like his mum, and settles for a seemingly casual "all right?"

"I just solved Lestrade's case for him." Sherlock carefully takes off his coat, and John sees the torn, bloodied shirt underneath. He jumps to his feet, concerned. "What happened to you?" He reaches out, and Sherlock flinches away. "It's nothing. Cat scratches."

They stare at each other awkwardly. John thinks that something has changed between them since yesterday.

"Hungry?" he asks, in an effort to restore normality.

"Yes."

"Go and sit down, I'll make you some cheese-on-toast."

But Sherlock doesn't sit down. Instead, he follows John into the kitchen, stands in the entrance.

"So how'd you solve it?" John says as he grates the cheese. Sherlock always takes great delight in talking him through the solution. But this time, to his surprise, Sherlock makes a non-committal noise and brushes the question away. "It's not important."

He puts the bread and cheese under the grill, boils up the kettle. Sherlock is watching his every move with cat-like eyes. It is disconcerting.

Then John has a realisation - Sherlock wants to talk about yesterday, but doesn't know how to begin.

So John says, "He didn't mean it, you know. Lestrade. He was just upset."

Sherlock does that flinching thing again, and suddenly becomes very interested in the contents of the fruit bowl. "It was my fault. I forgot that relationships are conditional."

John frowns. "What do you mean?"

"In every relationship, people continually weigh and measure each other. If either party is found wanting then the relationship is terminated."

"No, Sherlock, no," John says. "That's not how it works."

Sherlock looks up then. "It's exactly how it works, John. It's an unspoken contractual agreement, mutually dependent on the behaviour of either participant. And since I will always guarantee to offend everyone sooner or later, I must guard against entering in to such arrangements in the first place." Sherlock's eyes narrow suddenly. "Did Mrs. Hudson ever get you to sign the tenancy agreement?"

John can only stare at his flat mate. "Just - sit down," he says eventually.

When he enters the lounge, Sherlock is sitting on the sofa, interlocking and unlocking his fingers.

John places the toast and mug of tea in front of him. "Look, Sherlock. What you just said. Not all relationships are like that. Not the ones that matter, anyway. And if you're really concerned about offending people, then next time just look at me. I'll let you know when to shut up."

"What if you're not there?" Sherlock flashes back.

"I'll always be there." The words roll off his tongue automatically, but he is amazed at their effect. Sherlock brightens, and then he smiles that rare smile, the one that means he is pleasantly surprised by something. And it warms John's heart.

And so the next time Sherlock happens to comment on Molly Hooper's most recent wardrobe malfunction, he sees John's barely imperceptible shake of his head, and abruptly changes the subject to Clostridium spores.

And when he is about to question Mrs. Hudson on her latest liaison with the man who owns the newsagent down the street, he hears John mutter his name quietly and so he jumps up to put the kettle on instead.

And the next time he starts to insult Anderson for being so startlingly, so fundamentally _stupid_, he sees John frowning at him, and carries on regardless. Because Anderson has it coming.

_Finis_


End file.
